The boss of one of Britain's top 20 building societies has put out the welcome mat to carpetbaggers, people who open an account in the hope of a windfall if the society is taken over or bought by a bank.

Kent Reliance is scrapping the rule that makes new members agree to pay any windfalls to charity if the society is bought by a bank or floated on the stock market in their first five years of membership.

Its chief executive Mike Lazenby told BBC Radio 4's Money Box: "Our windfall assignment scheme was introduced five years ago to stop the disruptive impact of having speculative investors.

"Kent Reliance... would not be disrupted now by the impact of carpetbaggers and as a consequence we just want to be open to everybody."

Voting member

From 1 June anyone taking out a mortgage or opening a savings account or cash ISA with at least £100 will become a full voting member of Kent Reliance and will benefit from any future windfall if it is bought or taken over.

Mr Lazenby was clear that he did not rule out such a move.

"It is a very competitive market we are in. Costs are going up, margins are going down... so it is almost certain that many building societies will have to merge," he said.

In the future we may want to do a merger and... not necessarily with another building society

Mike Lazenby, Kent Reliance

"If we ever get to that point I don't necessarily want that to be with another building society, possibly run by backward-thinking inward-looking management."

But he stressed he would act in the best interests of members: "We have a duty to our members to do the best thing for them which may not be merging with another society.

"It is not going to happen tomorrow or next week or next year but at some stage in the future we may want to do a merger and... not necessarily with another building society."

What members might get if it was bought is uncertain.

Kent Reliance has assets of £1.3 billion and members of the similarly-sized Lambeth will get between £400 and £2,500 each when its current takeover by Portman goes through.

The charity clause will continue to apply to existing members who joined since June 2000.

They will have to wait for a full five years of membership before they can benefit from any windfalls.

Kent Reliance says they cannot leave and then join again.

>BBC Radio 4's Money Box was broadcast on Saturday, 20 May 2006, at 1204 BST and was repeated on Sunday, 21 May, at 2102 BST.